The β-amino alcohol 1b−Ti(Oi-Pr)4 complex has been shown to catalyze the enantioselective cyanosilylation of aldehydes efficiently. In the presence of 5 mol % of 1b−Ti(Oi-Pr)4 complex catalyst, the aromatic, conjugated, heteroaromatic, and aliphatic aldehydes were converted to their corresponding trimethylsilyl ethers of cyanohydrins in 90−99% yields with up to 94% ee under mild conditions.
β-氨基醇1b -Ti(O i -Pr)4配合物已显示出可有效催化醛的对映选择性氰基硅烷化反应。在5摩尔%的1b -Ti(O i -Pr)4络合催化剂存在下,芳族,共轭,杂芳族和脂族醛以90-99%的产率转化为相应的氰醇三甲基甲硅烷基醚,产率最高为94 %ee在温和条件下。
Highly enantioselective cyanosilylation of aldehydes catalyzed by a Lewis acid–Lewis base bifunctional catalyst
A new bifunctional asymmetric catalyst containing a Lewis acid and a Lewis base (1) was developed and applied to the catalytic asymmetric cyanosilylation of aldehydes. The products were obtained generally with excellent enantiomeric excess. The experiments using the control catalyst (5) and the catalyst containing more electron-rich phosphine oxide (6) suggest that the catalyst 1 should promote the
Development of a family of β-amino alcohol ligands with two stereocenters for highly efficient enantioselective trimethylsilylcyanation of aldehydes
作者:Jing-Song You、Han-Mou Gau、Michael C. K. Choi
DOI:10.1039/b006128j
日期:——
The asymmetric addition of Me3SiCN to aldehydes catalyzed by titanium(IV) complexes of N-sulfonylated derivatives of β-amino alcohols gave excellent ee’s up to 96% ee.
Room-temperature synthesis of enantioenriched non-protected cyanohydrins using acetone cyanohydrin as the cyanide source was achieved by V(salalen) catalyst. Aliphatic aldehydes underwent the cyanation with 89–95% ee in the presence of only 0.2–0.4 mol% catalyst. Aromatic cyanohydrins were also obtained in high enantiomeric excesses under modified conditions.
A new (R)-hydroxynitrile lyase from Prunus mume: asymmetric synthesis of cyanohydrins
作者:Samik Nanda、Yasuo Kato、Yasuhisa Asano
DOI:10.1016/j.tet.2005.08.105
日期:2005.11
A new hydroxynitrile lyase (HNL) was isolated from the seed of Japanese apricot (Prunus mume). The enzyme has similar properties with HNL isolated from other Prunus species and is FAD containing enzyme. It accepts a large number of unnatural substrates (benzaldehyde and its variant) for the addition of HCN to produce the corresponding cyanohydrins in excellent optical and chemical yields. A new HPLC